1. Field of the Invention
The present invention relates to the field of organic chemistry, chemical compositions thereof, and devices therefor employed as time watches, and depletion indicators for pesticides and insecticides.
2. State of the Art
Many devices are known that can be used for attachment to an animal such as a dog, cat, or cow and that contain an active ingredient that is controllably released to protect the animal against various parasites, insects, bacteria, and the like. These devices often have a useful life of from three to eight months, but there is no present way of determining in a simple, economical, and ready manner when the effectiveness of the active ingredient in the controlled release formulation has expired. Moreover, it is strongly desired by those in the art to employ a depletion indicator time watch that would be physically and chemically independent from the device ("parent device") for which depletion is to be measured, because (1) it would be sometimes convenient to watch the depletion indicator remote from the parent device, and (2) the active substance most often contains toxic substances for which it is further desirable to utilize a depletion indicator not containing toxic substances, for readily apparent safety reasons. The parent device most often contains a volatile controlled-release substance, which upon activation of the active substance is depleted or removed at a known predetermined rate.
It is known from U.S. Pat. No. 4,062,649 to Kuderna, issued Dec. 13, 1977, that the effective life of a controlled release formulation containing a volatile phosphate ester pesticide can be visually determined by using a mixture of an inorganic base which reacts with the ester, which comprises a suitable color-change indicator for acid/base reactions, an inert absorbent carrier, and a humectant. This mixture will contact a proportion of the pesticide vapor emitted therefrom. The amount of the base in the mixture is predetermined and directly related to the effective life of the formulation. The base is a necessary component of the mixture because it is required to react with the acid ester. When the indicator changes color to that of its neutral or basic form, the change signals the end of the effective life of the pesticide. It is necessary that a reaction take place between the ester and the inorganic base to form the corresponding salts during the course of operation of this visual indicator. However, Kuderna's device is both physically and chemically dependent on the parent device.
3. Description of the Prior Art
The prior art is perhaps best exemplified by German Offenlengungsshrift No. 2,519,126, which discloses an insecticidal device to be placed around the neck of a domestic animal, comprising:
(a) "Diazinon" and/or "Diazoxon" as an active ingredient; PA1 (b) a macromolecular vinyl or vinylidene compound; PA1 (c) a plasticiser; PA1 (d) optionally, a dye, a pigment, a stabilizer and a deodorant; and PA1 (e) optionally, a container
Normally, one would expect from the teachings of the art, including Kuderna et al above, that both an acid and base are needed to utilize a pH color indicator for an indicator for a pet collar. Surprisingly, I have found this not to be the case.